Seshiro: Your example is terrible. I make an identical function interface and an identical function signature and they work. I've been wasting 30 minutes of my time trying to reproduce all the freaking structs you use in that example and still not being able to get to the part in which it says the types are incompatible.
Edit: I have just reproduced all the structs , and the beast compiles correctly.
FriendlyPsycho: You need to be way more specific than that, I have been compiling interfaces and structs with stubs and all with the last version and it all works well to me, so try coming up with an actual example.